Molded explosive bodies having variable detonation speeds

ABSTRACT

Process of manufacturing molded explosive bodies so that their detonation speeds can be varied within a defined range by reducing the density of the molded body. The reduction in density can be effected by incorporating into the starting components, porous, voluminous or air containing materials. The solidification of the resulting compositions is thereafter carried out by incorporating into the above starting components a suitable binding agent, varying the working pressure in the forming of the bodies, or suitably regulating the sintering conditions. The resultant bodies are characterized by their reduced densities and therewith reduced detonation speeds and by their high mechanical strengths.

United States Patent Berthmann et al. 5] Dec. 9, 1975 MOLDED EXPLOSIVE BODIES HAVING 2,845,025 7/l958 Stark .1 149/93 x VARIABLE DETONATION SPEEDS t W 31m;

, arns e. [75] Inventors: Adolf Berthmann, Leverkusen;

Gerhard Martin, Troisdorf; Maximilian Klii'nsch, Opladen, all of Primary ExaminerLeland A. Sebastian Germany Attorney, Agent, or FirmBurgess, Dinklage & 73 Assignee: Dynamit Nobel AG, Troisdorf, Sprung Germany [22] Filed: Feb. 12, 1970 ABS CT [21 Appl. No.: 14,876

Process of manufacturing molded explosive bodies so R l ted A l I e a U S pp canon new that their detonation speeds can be varied within a de- [62] g g g gg g 7595M Sept 1968' fined range by reducing the density of the molded body. The reducttilon in density can be effected by incorporating 1nto e startmg components, porous, vo- [30] Foreign Apphcamm Pnonty Data luminous or air containin materials. The solidifi- 8 Germany 54099 cation of the resulting compositions is thereafter carried out by incorporating into the above starting com- [52] 149/2; 149/18? l4g/l9'6; ponents a suitable binding agent, varying the working 2 149M991; 149/93; 264/3 R pressure in the forming of the bodies, or suitably regug :g i

fg go z y lating the sintering conditions. l e 0 re The resultant bodies are characterized by their reduced dens1t1es and therewith reduced detonanon 264/3 R speeds and by their high mechanical strengths. [56] References Cited uNrrEo sTATEs PATENTS 3 Claims Drawmgs 2,255,3l3 9/l94l Ellis 1. 260/842 X MOLDED EXPLOSIVE BODIES HAVING VARIABLE DETONATION SPEEDS RELATED APPLICATION having variable detonation speeds within a defined range. More particularly this invention relates to homogeneous explosive bodies molded in any desired shape having detonation speeds with high mechanical strengths which can be adjusted as desired to values of between 1500 m/s and the maximum detonation speed of the specific explosive composition involved.

It is known that the detonation speed of explosives can be decreased by the addition thereto of inert substances. This procedure has only limited application, since the explosives sensitivity is so greatly diminished by very large additions of inert substances that the same are no longer capable of detonation.

Another possibility proposed for reducing the detonation speed is the reduction of the density of the explosive body by inclusion therein of air spaces. This is accomplished, for example, by compressing the explosives at different pressures. The compression effects a reduction of the density, but at the same time it produces a diminution of the mechanical strength of the resultant body, so that the density can be reduced in this manner only down to a certain limit. This in itself constitutes a considerable disadvantage.

It is an object of the invention to provide molded explosive bodies having reduced densities and therewith reduced detonation speeds.

Another object of the invention is to provide molded explosive bodies having reduced densities and therewith reduced detonation speeds characterized by high mechanical strengths.

A further object of the invention is to provide a process for producing molded homogeneous explosive bodies of the type described.

These and further objects of the invention are accomplished by sintering or binding with known binding agents explosive compositions, consisting of known solid explosives and air-containing, porous or voluminous materials.

In accordance with the invention there are accordingly provided explosive molded bodies having variable detonation speeds within a defined range, which are characterized in that in addition to the explosive agents, they contain porous, voluminous or air-containing materials.

The molded bodies according to the invention having the necessary strength characteristics and which are possessed of the required homogeneity can be prepared without the danger that the components of the mixture will separate out by heating a homogeneous mixture of the explosive and density reducing components too close to the melting point of the explosive component.

In the case of non-sinterable explosives, or if the sin tering temperature required is too high, a suitable sinand density reducing components and allowing the resultant compositions to set rather than using the sintering process. In this case the manufacture of the molded bodies is carried out, for example, by uniformly mixing the porous, voluminous, or air-containing materials with a binding agent and the explosive in finely powdered form, it being desirable in this connection for the grain size of the explosive to equal the grain size of the other components, since otherwise the danger that the components will become separated in the mixture exists. The mixture is then put into a mold which is closed with a plunger and pressed. The pressure employed ranges preferably between O.l and l kglcm though it may be lower or higher. To achieve bodies of equal volume and hence of equal density, the movement of the plunger can be limited while the same quantity is always charged.

When the sintering process is used, in which case the addition of the binding agent can be omitted, i.e. the explosive itself serves as the binding agent, and then the filled molds are brought to a temperature just under the melting temperature of the explosive. The sintering temperature depends on the purity of the fusible explosive component used, or the melting point of the eutectic mixture if mixtures are used. The sintering temperature can also be raised above the melting point if the percentage of the component or mixture thereof that is to be melted, (i.e. the amount of fusible mixture or explosive) is so low that no separation of the mixture takes place. The most important sintering explosive involved is trinitrotoluene (TNT). However, explosives or explosive mixtures can also be advantageously used which are still sufficiently stable at their melting temperature and which do not tend to undergo separation. The pressure in the sintering process amounts preferably to O.l to l kplcm though it may be higher or lower. After the mixture has set or cooled in the sintering process, the bodies, which until then have been kept under pressure, are removed from the mold.

The explosives which can be used according to the invention include, for example:

a. Aromatic nitro substances, such as trinitrobenzene,

trinitrotoluene, trinitroanisole, trinitrocresol, trinitrophenol (picric acid), trinitrophenetol, trinitroresorcinol, trinitromethylaniline, trinitrophloroglucine, hexanitrodiphenylamine, (hexyl) hexanitrodiphenyl, hexanitrodiphenylsulfide, hexanitrodiphenylsulfone, hexanitroazobenzene.

b. Nitramines, such as cyclotrimethylenetrinitramine (hexogen), trinitrophenylmethylnitramine (tetryl), cyclote tramethylenetetranitramine (octogen ethylenedinitramine.

c. Nitrosamines, such as cyclotrimethylenetrinitrosamine.

(1. Nitric acid esters, such as pentacrythritol tetranitrate.

e. Ammonium nitrate admixed with a combustible substance.

As air-containing materials there come into consideration the materials which consist of individual gas-filled hollow bodies, such as microbubbles (hollow spheres of phenolic or urea resin), and closed-pore foam plastic.

As porous materials there are intended the substances which are filled with fine air spaces, but whose openings to the surface of the particles are nevertheless so small that viscous liquids (for instance, adhesives) cannot appreciably penetrate therein.

compounds.

b. Inorganic binding agents to which water is added and which set as a result of the addition of water, for instance, plaster of Paris, Portland cement, magnesium cement, minium-glycerin cement, and other like mixtures.

The explosive molded bodies obtained by the process of the invention have such great strength that they can after their production be subjected to mechanical working.

By combining molded explosive bodies having different detonation speeds, systems can be formed which form a shock wave front of any desired shape when they are detonated.

The invention is illustrated by the following examples. The same are, however. not to be construed in limitation thereof.

The percentage of air-containing materials and/or porous materials and/or volumious materials in the molded explosive bodies is 0.1 to 40 preferably 1 to based on the explosive composition. 30

The binding agents cited sub (a) are used in an amount of 2 to 40 preferably 5 to 25 based on the explosive composition.

The binding agents cited sub (b) are used in an amount of 4 to preferably 10 to 25 based on 35 the explosive compositionv EXAMPLES l 4 Examples 1 4 describe the manufacture of molded explosive bodies using the sintering method which has to reduce the density, or alternatively cork flour was used for this purpose.

The quantities of the components which were used in each case, the conditions of manufacture and the detonation speeds, are set out in the following table:

TABLE 1 Example I 2 3 4 TNT, ground(wt-%] 100 89 73 9O Microbubbles (wt%) (1 11 27 Cork flour (wt-%) 10 Density. g/cm 1.1 0.74 0.4 0.3 Sintering pressure (kp/cm) 0.5 0.2 0,4 0.3 Sintering temp. in C 79 79 79 8O Sintering time, hours 5 5 5 5 Detonation speed, m/s 5700 3360 [500 2710 EXAMPLES 5 7 In Examples 5 7 the manufacture of molded explosive bodies is also carried out by the sintering process, but in this instance the binding agent was not the explosive itself, but rather an explosive (TNT) which is used additionally in small amounts for this purpose. Wood flour, cork flour and the microbubbles as used in Examples l 4 were employed to reduce the density. The quantities in which the components were employed in each case, the manufacturing conditions and detonation speeds, are reported in the following table:

TABLE 11 Example 5 6 7 Ammonium nitrate (wt-%] 85 77 74 TNT, ground (wt-7( l0 l4 l3 Microbubbles (wt-] S Wood flour (wt-%] 9 Vegetable flour (wt-70] 13 Density, g/cm" 0.8 0.85 l.l Sintering pressure,(kp/cm 0.3 0.3 0.3 Sintering temp. in "C 80 8O sintering time. hours 5 6 6 Dentonation speed, m/s 2350 2290 3670 EXAMPLES 8 20 Examples 8 10 and 14 20 describe the manufacture of the molded explosive bodies using a binding agent which sets without heating. Such agents include adhesives sold under the trade names Araldit", Adhesin", Pattex" and UHU, as well as plaster of Paris and Portland cement. (The trade names are more precisely defined in the following summary.)

Examples 1 l 13 are specifically concerned with the manufacture of the molded explosive bodies using the sintering process, in which an inert compound without properties of an explosive serves as the binding agent.

The quantities of the components, the manufacturing conditions as used in Examples 8 20, and the detonation speeds are reported in the following table. The microbubbles which have been used are the same as those which were used in Examples 1 4.

TABLE Ill Examples 8 9 10 ll 12 13 l4 15 16 17 Nitropenta lwbi) 76 72 56 90 75 63.2 56.6 8| Bl Microbubbles 4 B 24 5 1O 15 3.4 10 l0 l0 Centralit l 5 5 l0 Araldir 20 2U 2U Adhesin 3 3.4 33.4

IR registered trademark] Pattex 9 l'HU 9 Density g/cm (L87 [L73 11.58 0.62 ().SI (],48 0.87 U57 U.7'l 0.67 Compression pressure 0.1 0.1 0.1 0.2 0.2 0.2 0.1 ().l l).| 0.1

kplcm' Sintering temp. C as 86 86 sintering time, hours 5 5 TABLE Ill-continued Examples 8 9 ll l2 l3 l4 l5 l6 l7 Detonation speed. m/s 47l0 4280 3220 4185 3370 32l5 4730 3220 4226 4300 Centralit l Diethyldiphenyl urea Araldit Synthetic glue made from ethoxylin resins (cold setting twocomponent plastic) Adhesin Polyvinyl acetate Pattex Contact cement made from polychkirobutadiene plus resins and organic solvents UHU All-purpose cement (polyvinyl resin plus solvent) Examples l8 I9 Percentages by weight Nitropenta 60 5 60 Microbubbles 20 l 5 20 Plaster of Paris 20 20 Portland cement 20 Water added per l00g 60 60 60 of mixture (cm Density (g/cm") 0.36 0.42 0.46 Compression pressure (kp/cm) 0.l (H 0.1 Detonation speed (m/s) 2l 10 3440 3610 We claim:

1. A homogeneous high strength molded explosive body comprising a solidified mixture of solid pentaerythrite-tetranitrate explosive, hollow spheres of phenolic resin density reducing material and diethyldiphenyl urea binding agent, said molded explosive body having a detonation velocity within a defined range, said detonation velocity being less than the detonation velocity of the explosive itself, said pentaerythrite-tetranitrate uniformly mixed with said hollow spheres and said binding agent.

2. A homogeneous high strength molded explosive body comprising a solidified mixture of solid pentaerythrite-tetranitrate explosive, hollow spheres of phenolic resin density reducing material and a hardenable cold setting plastic based on ethoxylin resins as binding agent, said molded explosive body having a detonation velocity within a defined range, said detonation velocity being less than the detonation velocity of the explosive itself, said pentaerythrite-tetranitrate uniformly mixed with said hollow spheres and said binding agent.

3. A homogeneous high strength molded explosive body comprising a solidified mixture of solid pentaerythrite-tetranitrate explosive, hollow spheres of phenolic resin density reducing material and a polyvinylacetate adhesive binding agent, said molded explosive body having a detonation velocity within a defined range, said detonation velocity being less than the detonation velocity of the explosive itself, said pentaerythrite-tetranitrate uniformly mixed with said hollow spheres and said binding agent. 

1. A HOMOGENOUS HIGH STRENGTH MOLDED EXPLOSIVE BODY COMPRISING A SOLIDIFIED MIXTURE OF SOLID PENTAERYTHRITE-TETRANITRATE EXPLOSIVE, HOLLOW SPHERES OF PHENOLIC RESIN DINSITY REDUCING MATERIAL AND DIETHYLDIPHENYL UREA BINDING AGENT, SAID MOLDED EXPLOSIVE BODY HAVING A DETONATION VELOCITY WITHIN A DEFINED RANGE, SAID DETONATION VELOCITY BEING LESS THAN THE DETONATION VELOCITY OF THE EXPLOSIVE INSELF, SAID PENTAERYTHRITETETRANITRATE UNIFORMLY MIXED WITH SAID HOLLOW SPHERES AND SAID BINDING AGENT.
 2. A homogeneous high strength molded explosive body comprising a solidified mixture of solid pentaerythrite-tetranitrate explosive, hollow spheres of phenolic resin density reducing material and a hardenable cold setting plastic based on ethoxylin resins as binding agent, said molded explosive body having a detonation velocity within a defined range, said detonation velocity being less than the detonation velocity of the explosive itself, said pentaerythrite-tetranitrate uniformly mixed with said hollow spheres and said binding agent.
 3. A homogeneous high strength molded explosive body comprising a solidified mixture of solid pentaerythrite-tetranitrate explosive, hollow spHeres of phenolic resin density reducing material and a polyvinylacetate adhesive binding agent, said molded explosive body having a detonation velocity within a defined range, said detonation velocity being less than the detonation velocity of the explosive itself, said pentaerythrite-tetranitrate uniformly mixed with said hollow spheres and said binding agent. 